The dark chocolate cookies provide a stunning backdrop for the lacey white drizzle. Be sure the icing is thin enough to drizzle in a fine stream.
Heat oven to 375 degrees F. Sift together flour, cocoa powder, baking soda and salt into a medium-size bowl.
Beat butter in large bowl until creamy. Add brown and granulated sugars; beat until fluffy. Beat in eggs, one at a time. Beat in vanilla.
On low speed, beat in flour mixture. Gently fold in chips. Drop by heaping teaspoonfuls, about 2 inches apart, onto ungreased baking sheets.
Bake in 375 degree F oven 9 to 11 minutes, until crisp. Cool on sheet on rack 2 minutes. Transfer to rack.
Beat together sugar, mint extract and water in small bowl until smooth. Transfer to plastic food-storage bag; snip off corner. Drizzle over cooled cookies. Let stand until glaze is set.